<template>
  <div class="star" :class="starType">
    <span
      v-for="(itemClass,index) in itemClasses"
      :key="index"
      :class="itemClass"
      class="star-item"
    ></span>
  </div>
</template>
<script>
const LENGTH = 5;
const CLS_ON = "on";
const CLS_HALF = "half";
const CLS_OFF = "off";
export default {
  props: {
    size: {
      type: Number
    },
    score: {
      type: Number
    }
  },
  data() {
    return {
      itemClass: ""
    };
  },
  computed: {
    // 星星类型
    starType() {
      return "star-" + this.size;
    },
    // 星星类型数组处理
    itemClasses() {
      let result = []; // 盛放全星、半星、空星的类名
      let score = Math.floor(this.score * 2) / 2; // 将评分转成整数或者4.5这样的数；

      // 计算全星，半星，无星
      let hasDecimal = score % 1 !== 0; // 是否有半星

      let integer = Math.floor(score); // 计算整星的个数
      // 遍历，将全星的类加进去
      for (let i = 0; i < integer; i++) {
        result.push(CLS_ON);
      }
      // 如果有半星，将它这个类添加进去
      if (hasDecimal) {
        result.push(CLS_HALF);
      }

      while (result.length < LENGTH) {
        result.push(CLS_OFF);
      }
      return result;
    }
  }
};
</script>
<style lang="stylus">
.star {
  font-size: 0;

  .star-item {
    display: inline-block;
    background-repeat: no-repeat;
  }

  &.star-48 {
    .star-item {
      width: 20px;
      height: 20px;
      margin-right: 22px;
      background-size: 20px 20px;

      &:last-child {
        margin-right: 0;
      }

      &.on {
        background-image: url('./star48_on@2x.png');
      }

      &.half {
        background-image: url('./star48_half@2x.png');
      }

      &.off {
        background-image: url('./star48_off@2x.png');
      }
    }
  }

  &.star-36 {
    .star-item {
      width: 15px;
      height: 15px;
      margin-right: 6px;
      background-size: 15px 15px;

      &:last-child {
        margin-right: 0;
      }

      &.on {
        background-image: url('./star36_on@2x.png');
      }

      &.half {
        background-image: url('./star36_half@2x.png');
      }

      &.off {
        background-image: url('./star36_off@2x.png');
      }
    }
  }

  &.star-24 {
    .star-item {
      width: 10px;
      height: 10px;
      margin-right: 3px;
      background-size: 10px 10px;

      &:last-child {
        margin-right: 0;
      }

      &.on {
        background-image: url('./star36_on@2x.png');
      }

      &.half {
        background-image: url('./star36_half@2x.png');
      }

      &.off {
        background-image: url('./star36_off@2x.png');
      }
    }
  }
}
</style>
